Carlson Real Estate is about to sell the Plaza Seven office building at 45 Seventh St. S. in downtown Minneapolis for an undisclosed sum.

It's being bought by San Francisco-based City Center Realty Partners, according to sources familiar with the deal who asked not to be named to protect client relationships. The deal could close as soon as Thursday.

Officials for Carlson couldn't be reached for comment. A spokeswoman for City Center Realty declined to comment.

UPDATE: The deal closed Thursday, as expected. City Center disclosed that it did the deal in partnership with New York-based Angelo, Gordon & Co., a privately held investment advisor that manages about $25 billion in assets, according to a news release.

City Center Retail will put in some capital to renovate aspects of the office building, especially the elevator system, although a major overhaul probably isn't needed. Carlson completed a multimillion dollar renovation of Plaza Seven in 2012.